System for detection of unfastening or removal of absorbent article from the body

ABSTRACT

A method for detecting and conveying an alarm signal, when an absorbent article is unfastened or, completely removed from the body of the wearer. The method is intended to be used in parallel with a method for detecting wetness in the absorbent article and further relates to an integrated detection-and-alarm method for detecting unfastening and/or wetness in an absorbent article. A system for detecting and conveying an alarm signal when an absorbent article is unfastened or removed from the body of the wearer and/or when the article is wet. The system includes (a) and absorbent article having at least one absorbent layer, the object to be displaced, such as a fastening system, one or more sensoring devices, one or more transmitting devices, and (b) a remote receiver. Furthermore, the system relates to the use of the system in the care of children and adults suffering from incontinence and/or psychological illnesses.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of PCT/SE2005/001142, filedJul. 11, 2005, the entire contents of which is incorporated herein byreference.

FIELD OF THE INVENTION

This disclosure relates to a method for detecting when an absorbentarticle is unfastened or alternatively, completely removed from the bodyof the wearer, and when so, remotely indicate said unfastening. Thedisclosure is intended to be used in parallel with a method fordetecting wetness in the absorbent article and further relates to anintegrated detection-and-alarm method for detecting unfastening and/orwetness in an absorbent article. The disclosure further relates to asystem for detecting when an absorbent article is unfastened or removedfrom the body of the wearer and/or when said article is wet, and whenso, conveying an alarm signal. Furthermore, the disclosure relates tothe use of said system in the care of children and adults suffering fromincontinence and/or psychological illnesses, such as dementia.

BACKGROUND

Absorbent articles, such as diapers for infants and adults, sanitarynapkins, and adult incontinence garments, are well known within the artand used widely. Most such products today are used on a single-usebasis. The single-use basis of such disposable products have led to thedevelopment of a wide assortment of different products to meet specificrequirements, e.g. in infant and toddler care, as well as in adultssuffering from incontinence. The main purpose of such absorbent articlesis normally to absorb, retain and isolate body waste products, such asurine, feces or blood.

Absorbent articles which respond to an event, such as urination ordefecation, related to the absorption of a fluid into or onto theproduct, are also well known within the art. This response is normally asignal after the event has occurred and is based on a measure of, forexample, wetness, temperature or mass change. The signal may be anoptical signal, including visual signals, an audio signal, a chemicalsignal or an electrical signal. The signal can give the wearerhimself/herself or nursing aid feedback information that an event hasoccurred, which would ease clean-up procedures for both parties.

Many of these articles incorporate sensors, the latter of which mayfunction in a wide variety of ways. For example:

WO 2004/021944 discloses a disposable sensoring absorbent structure fordetecting wetness, comprising at least one absorbent layer and at leastone sensing device comprising a magnetoelastic film. The absorbentstructure enables means and methods for monitoring the status, e.g.wetness, at least one biological analyte and/or at least one chemicalanalyte, in an absorbent article.

WO 00/16081 discloses a system comprising a resonant circuit which is atleast partly formed from a moisture sensitive material, the electricalresistance of which increases when the material comes into contact withmoisture. The system also comprises at least one electronic sensor fordetecting the presence of moisture, and at least one reading device forobtaining information from the sensor about the presence of moisture.

U.S. Pat. No. 5,808,554 discloses a garment diaper detector fordetecting wetness conditions in diapers or undergarments comprising acapacitive sensor located within a housing and affixed to the exteriorsurface of the garment being monitored. The sensor is comprised of twosubstantially solid, coplanar conductor plates affixed to a commonsubstrate and has a very high dynamic range. When the inside of thegarment becomes wet, the capacitance between the spaced conductors risesabove a predetermined value whereupon the detector provides an output toa transmitter or an alarm. One particular group of direct users orwearers of such absorbent articles would include psychiatric patientssuffering from dementia or other psychological illnesses, whoadditionally suffer from varying degrees of incontinence. These personsmay not feel any inhibitions about excretory functions and may removetheir incontinence garments either before urination/defecation orimmediately after, thereby contaminating themselves and/or theirsurroundings, resulting in unpleasant clean-up activities for thenursing staff.

In such a case, the presence of an “unfastening” sensor or detector inthe incontinence garment would be contemplated to be of great utilityand advantage. Such a sensor would register and raise an alarm when theincontinence article is unfastened or completely removed from the bodyof the wearer.

The presence of a removal sensor would also be anticipated to be ofutility for normal wearers such as children or persons suffering fromincontinence problems, where, for example, the accidental removal ofabsorbent articles during sleep would lead to an alarm signal. None ofthe above cited art describes absorbent articles comprising a sensor fordetection of unfastening or complete removal from the body of thewearer.

OBJECTS AND SUMMARY

The disclosure provides a method for detecting when an absorbent articleis unfastened or alternatively, completely removed from the body of thewearer and conveying an alarm signal to the direct user or wearer, orindirect user, such as the nursing staff.

The method comprises (a) detecting the displacement of at least oneobject, such as a fastening device, and (b) conveying an alarm to aremote receiver.

Said method may be used in parallel with a method for detecting wetnessin the absorbent article, such as the method disclosed in patentapplication WO 2004/021944, which is incorporated herein by reference.The method is a method for remotely detecting when an absorbent articleis unfastened or removed from the body of the wearer comprising thefollowing steps:

-   -   providing said absorbent article with a fastening system        comprising at least a first and a second part, said parts being        devised to be separated when the absorbent article is not        attached to the wearer, and being devised to be close together        when said article is attached to the wearer, where said first        part is provided with an area that has the capability of        influencing a resonant entity arranged at or close to said        second part of said fastening system;    -   fastening said absorbent article to a wearer—reading a resonant        frequency and/or a signal strength of a signal emitted from said        resonant entity;    -   determining, based on said read frequency and/or signal        strength, the state of the absorbent article as being        unfastened/removed on the one hand or correctly fastened on the        other hand. In one type of embodiments said resonant frequency        assumes a first value when the absorbent article is correctly        fastened to the wearer, and a second value when the absorbent        article is unfastened or removed from said wearer. The method in        this case further comprises the steps of determining whether a        read frequency is the first frequency or the second frequency.        The disclosure further relates to the use of said integrated        method in the manufacture of a system for detecting and        conveying an alarm signal when an absorbent article is        unfastened or removed from the body of the wearer and/or when        said article is wet.

The disclosure thus relates also to a system for detecting and conveyingan alarm signal when an absorbent article is unfastened or removed fromthe body of the wearer and/or when said article is wet.

According to a preferred embodiment, the system comprises (a) anabsorbent article comprising at least one absorbent layer, the object tobe displaced, such as a fastening system, one or more sensing devices,one or more transmitting devices, and (b) a remote receiver.

In one embodiment, the one or more sensing device(s) detectsoscillational differences arising due to an increase or a decrease inthe magnetic bias-field corresponding to the displacement of saidobject. In such an embodiment, the preferred sensing device is amagnetoelastic film.

In another embodiment, the one or more sensing device(s) comprises aresonant circuit comprising inductive, capacitive and connectiveelements, and where at least one of said elements are arranged such thatan electrical property of said element or elements are changed when theabsorbent article is displaced or removed.

In one embodiment, the system comprises a remote receiver which is ahandheld unit.

In another embodiment, the system comprises a remote receiver which is astationary unit. In another aspect, it relates to the use of said systemin the care of children and adults suffering from incontinence and/orpsychological illnesses, such as dementia.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a belt-diaper (1) having a general T-shaped configurationand comprising an absorbent structure (2) and a fastening device in theshape of a belt (3).

FIG. 2 shows the diaper (1) just before fastening of the front part (19)of the diaper (1) to the belt (3).

FIGS. 3 a and 3 b show an “open diaper” embodiment of the belt-diaper(1), in an unmounted state, FIG. 3 a and in a mounted state, FIG. 3 b.

FIGS. 4( a) and (b) show the frontal and side view illustrations of thehook fastening device (401) comprising a carrier material.

FIGS. 5( a) and (b) show the frontal and side view illustrations ofanother embodiment of the fastening device, where the permanent magnetis free from the hook material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Definitions

As used herein, the term “absorbent article” refers to a device thatabsorbs, retains and contains body waste or body exudates, such asurine, feces or blood.

In use, the device is placed against or otherwise positioned in closeproximity to the body of the wearer.

The term “disposable” refers to an absorbent article which is notintended to be laundered, restored or reused as an absorbent article.Such an absorbent article is intended to be discarded after a singleuse. The single use does not however, exclude the product from beingrecycled, made into compost or otherwise disposed of, in anenvironmentally compatible manner.

The term “sensor”, “sensing device” or “detector” is usedinterchangeably and herein intended to mean a device that is capable ofdetecting an event or alternatively, a parameter that is associated withan event. A parameter associated with an event is any measurable signalthat correlates with the occurrence of an event within the framework ofthe system, i.e., a signal caused by the waste, the wearer, or acomponent thereof. Sensors include all embodiments responding to one ormore specific inputs.

The term “sensoring” or “sensing” or “detecting” refers to means andmethods capable of detecting an event or a parameter associated with anevent, using, for example, a sensoring device.

The term “wetness” is herein intended to mean the condition of beingwet, humid, damp or alternatively, containing or being covered by aliquid, especially water.

The term “diaper” is herein intended to mean an absorbent articlegenerally worn about the lower portion of the torso by infants, toddlersand persons suffering from incontinence. The term “user” as used hereinmay refer to (a) the direct user or wearer of an absorbent article, oralternatively, (b) the indirect user or nursing personnel who haveresponsibility for the care of the wearer of the absorbent article.

The term “magnetostriction” refers to a common phenomena observed inmagnetic materials, and is said to occur when the dimensions of amagnetic material change after being magnetized. The size or enormity ofthe dimensional change depends on temperature, magnetization in thematerial and of course, on the material properties. Magnetostriction isdue to the interaction between the atomic magnetic moments in thematerial.

The term “magnetoacoustic resonant frequency” refers to an oscillationfrequency which is manifest when a magnetic material is excited by amagnetic field and stores magnetic energy in a magnetoelastic mode. Whenthe magnetic field is switched off, the material shows dampedoscillation with a specific frequency, refered to as the magnetoacousticresonant frequency.

The term “carrier material” as used herein refers to the material orfabric covering the hook fastening device, as depicted in FIG. 4. Thecarrier material may be, for example, a spunbonded nonwoven with a basisweight of about 25-60 g/m². It is preferably made of polyproplyenefibers. However, any conventional material may be used.

The term “resonant circuit” as used herein refers to an electric circuitwhere the impedance or the damping of said circuit is frequencydependent.

The term “resonant entity” refers to an entity, being electric,magnetic, mechanic, magnetostrictive or otherwise in nature, where thedamping of said entity is frequency dependent.

Terminology and Related Subject Matter:

Absorbent Article

In normal use, an absorbent article, such as a diaper, a diaper of areclosable pant type, an incontinence garment, a sanitary napkin, servesto absorb, retain and isolate body wastes or body exudates anddischarges, for example, urine, feces, blood, menstruation blood, fluidmatter from wounds and sores.

In one embodiment of the absorbent article, the absorbent layercomprised in the absorbent article, comprises at least one acquisitionlayer, at least one storage layer, and optionally one or more wickinglayers. The acquisition layer is intended to take up fluid and todisperse said fluid to the wicking and storage layer(s).

In another embodiment, at least one of the above said acquisition,storage or wicking layer(s) comprises 0-100% superabsorbent material.

In further embodiments, said acquisition, storage or wicking layer(s)may comprise 0-95%, 20-100%, 0-30%, 20-90%, or 30-40% of superabsorbentmaterial.

Hook and Loop Fastening

Hook and loop fastening refers to a type of VELCRO fastening, i.e., afastening method where one of the surfaces that are to be joinedcomprises a plurality of small hooks. The other surface comprises aplurality of small loops.

Magnetoelastic Film

A magnetoelastic film is one type of magnetoelastic sensor.Magnetoelastic sensors have been described by Grimes et al., (BiomedicalMicrodevices, 2:51-60, 1999).

When a magnetic material is excited by an externally applied magneticpulse or field, it stores magnetic energy in a magnetoelastic mode. Whenthe field is switched off, the material shows damped oscillation with aspecific frequency, the magnetoacoustic resonant frequency. Theseoscillations give rise to a magnetic flux that varies with time, whichcan be remotely detected by a pick-up coil.

The changes in resonant frequency may be monitored so as to measure ordetect multiple environmental parameters. Measurements of temperature,pressure, viscosity, using this method are described in Grimes et al.(Biomedical Microdevices, 2:51-60, 1999).

It is also possible to excite the material with a continuous magneticfield showing a frequency corresponding to or close to themagnetoacoustic resonant frequency and measure the response from thematerial instead, such as the damped magnetic response from the materialbetween the pulses. At the resonant frequency the response from thematerial is maximal.

Additionally, when a magnetic field is applied to a magnetic material,such as a ferromagnetic material, the dimension of the material changes.This effect is called magnetostriction, as defined earlier. The size ofthe dimensional changes of the material is governed by themagnetostriction constant. Magnetostriction can be observed in manymaterials, for instance, in iron, nickel, cobolt, rare earth metals aswell as in different alloys such as iron-nickel alloys, ferrites, e.g.spinel type ferrites (Fe₃O₄, MnFe₂O₄), and silicon-iron alloys.

The magnetoelastic film used in the invention shows magnetorestrictionand may also comprise amorphous magnetic material, alloys or mixturesthereof. Amorphous magnetic material is very easy to magneticallysaturate and shows a small magnetic anisotropy. In alloyed amorphousmagnetic material, magnetostriction is also present, and the amount ofmagnetostriction depends on the exact composition of the alloy. Examplesof amorphous alloys are metglases such as Fe₄₀Ni₃₈Mo₄B₁₈, e.g. Metglas282MB™ (Honeywell Amorphous Metals, Pittsburg, Pa., USA), (FeCo)₈₀B₂₀,(CoNi)₈₀B₂₀, (FeNi)₈₀B₂₀.

One embodiment uses METGLAS® material from Honeywell (HoneywellAmorphous Metals, Pittsburg, Pa., USA) as the magnetoelastic material,such as METGLAS® 2826MB.

Suitable magnetoelastic films may be any film possessing a non-zeromagnetostriction and a high magnetoelastic coupling, such as aniron-nickel alloy, rare earth metals, ferrites, and the different alloysand mixtures disclosed above. A suitable film thickness of saidmagnetoelastic films is about 0.01-1000 μm, such as from about 0.01 toabout 200 μm, such as from about 5 to about 100 μm, such as from about0.01 to about 100 μm. The thickness of the film may be much less thanthe width and the length of the film.

One way of further enhancing the magnetostrictive effect is to include amagnetic bias field. A magnetic bias field has an optimal magnetic biasfield, giving an optimal magnetoacoustic effect, and further giving anoptimal signal from the magnetoacoustic effect (Grimes et al., Sensorsand Actuators, B71:112-117, 2000). In one embodiment, the magnetic biasfield is generated by a permanent magnet, placed in connection with themagnetoelastic film. The permanent magnet may be in the form of smallmetallic pieces of various shapes and sizes (such as those useddomestically as kitchen pin-up devices on the refrigerator), powder,granules, film, magnetic ink, and other forms.

The disclosed embodiments provide a convenient and inexpensive methodfor detecting and conveying an alarm signal to the direct user (such asthe wearer), or indirect user (such as the nursing staff), when anabsorbent article is unfastened or alternatively, completely removedfrom the body of the wearer.

The alarm signal thus represents feedback information that an event hasoccurred.

The embodiments would also permit convenient monitoring, through remoteaccess, of the status of the wearer (i.e., absorbent article on or off),as well as continuous monitoring of the status over time by the nursingstaff.

The method comprises (a) detecting the displacement of at least oneobject, such as a fastening device, and (b) conveying an alarm to aremote receiver. The remote receiver may be in the form of a handheldunit or a stationary unit permanently placed at a suitable location.

Said method is intended to be used in parallel with a method fordetecting wetness in the absorbent article, such as the method disclosedin patent application WO 2004/021944, described briefly in thebackground section and which is incorporated here by reference. Saidmethod disclosed the use of a sensoring device comprising amagnetoelastic film with a thickness of between about 0.01-1000 μm fordetecting the presence of moisture and/or biological analytes andchemical analytes. The present disclosure thus further relates to anintegrated detection-and-alarm method for detecting unfastening and/orwetness of/in an absorbent article.

The disclosure further relates to the use of said integrated method inthe manufacture of a system for detecting and conveying an alarm signalwhen an absorbent article is unfastened or removed from the body of thewearer and optionally when said article is wet.

The disclosure thus relates also to a system for detecting and conveyingan alarm signal when an absorbent article is unfastened or removed fromthe body of the wearer and optionally when said article is wet.

According to a preferred embodiment, the system comprises (a) anabsorbent article comprising at least one absorbent layer, the object tobe displaced, such as a fastening system, one or more sensing devices,one or more transmitting devices, and (b) a remote receiver, whichhouses a pick-up coil. In one embodiment, the one or more sensingdevice(s) detects oscillational differences arising due to an increaseor a decrease in the bias-field corresponding to the displacement ofsaid object. Said sensing device may be small, optionally removable andreusable, involve a wireless, battery-less circuit, is coupled with analarm transmitter and remote receiver. The sensing device may bepackaged or encapsulated as protection against damage from, for example,mechanical pressure, which may affect the resonant frequency. Suitableencapsulation forms include encapsulation in the form of tags such asthe commercially available tags from, e.g., Sensomatic (Wien, Austria),or a similar product. The encapsulation is designed or chosen in eachcase by the skilled man to fit a specific embodiment.

In a preferred embodiment, a magnetoelastic film is employed as thesensoring device. One or more sensors may be used. Furthermore, a thinribbon of a magnetoelastic material may be used. The magnetoacousticresonant frequency for, for example, a thin ribbon of a magnetoelasticmaterial is inversely proportional to the length of the ribbon. Thus, itis possible to achieve different resonant frequencies in one sensoringdevice. A typical magnetoelastic material which could be used in theinvention is METGLAS material from Honeywell (Morristown, N.J.) In oneembodiment, a magnetic bias field is generated, and a resonant entity isprovided, through the presence of, for example, one or more permanentmagnets which are connected to, or placed in a defined position, withrespect to the one or more sensors. The permanent magnets are attachedto one or more fastening devices of said absorbent article by any methodcommonly used in the art, or may be employed as a part of the fasteningdevice. The permanent magnets may be in the form of small metallicpieces of various shapes and sizes, powder, granules, film, magneticink, or other forms.

When the fastening device(s) are moved away from the sensor(s), as inthe situation when the absorbent article is unfastened, the magneticfield will change and the sensor(s) detect oscillational differencesarising due to an increase or a decrease in the bias-field correspondingto the displacement of said fastening device(s). As an example, in adiaper-type garment, the sensor response might involve a resonant entitywhich detects whether the fastening device such as a tape or a belt isin contact with the front panel of the diaper.

This effect is supported by studies in the literature (Ohizumi, S.,“Physics of Ferromagnetism”, Oxford, Oxford University Press, 1997;O'Handley, R. C., “Modern Magnetic Materials, Principles andApplications”, New York, John Wiley & Sons Inc., 2000). A comparison ofthe magnetoacoustic effect appearing when a magnetic bias field is firstapplied, or alternatively, as in this example, obtained from a permanentmagnet (a) in the neighborhood of a magnetoelastic (such as METGLAS®)film), and then (b) over said film, shows that the signal from themagnetoacoustic oscillations increases significantly, and that it iseven possible to see higher harmonics of the magneto-acousticoscillations. This is due to the fact that the magnetoelastic effect isenhanced when the magnetic field is increased over the sample.

The amplitude of the applied magnetic field should be large enough tomagnetize the material, such as the magnetoelastic film, to a certainamount in order to achieve a sufficiently large change in materialdimensions. The specific magnetic fields may therefore be optimized foreach magnetostrictive material chosen.

A magnetic field amplitude of, for example, 0.06 mT at the film, hasbeen assessed by the inventors to be high enough in order to detectmagnetoacoustic signals. Magnetic pulses of 1 kHz with a duty cycle of20% are typically used, but other frequencies and duty cycles may alsobe used. A magnetic field in the range of 0.05 mT to 0.1 mT will createsufficient magnetization in the magnetoelastic film. The exact valuedepends on the chosen material in the magnetoelastic film, and may thusbe optimized for each embodiment. The exact values of the pulsefrequency, duty cycle and field amplitude at the film could, in asimilar way, be optimized when the material of the magnetoelastic filmand the application of the sensor system are chosen. Also, the distanceof the remote receiver of the alarm signal (such as a handheld orstationary unit) should be considered here and the value of the maximumdistance between the remote receiver and the magnetoelastic film shouldbe defined when optimizing other parameters in the differentembodiments. The minimum distance is at the outer surface of theabsorbent article. The detection may be designed to enable the largestcovering range about x m, where x is chosen by, for example, the nursingpersonnel, by proper design of an excitation coil and a pick-up coil.

In one embodiment, the detection may be designed to enable the largestcovering range about x m, where x is about 0-10 m, such as about 0, 1,2, 3, 4, 5, 6, 7, 8, 9, or 10 m.

In a further embodiment, the detection may be designed to enable thelargest covering range about x m, where x is about 0-5 m.

In still a further embodiment, the detection may be designed to enablethe largest covering range about x m, where x is about 0-1 m, such asabout 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 m.

Detection of the magnetoacoustic resonant frequency is effected throughthe pick-up coil housed within the remote receiver, which detects theresponse from the material.

In one embodiment, the system comprises a remote receiver which is ahandheld unit. A typical remote receiver in the form of a hand held unithas already been described in WO 2004/021944 A1, which is incorporatedby reference. The signal generator is connected to the detection circuitso that the detection circuit “knows” when a signal is sent to theexcitation coil. Furthermore, the remote receiver, such as in the formof a hand held unit, may be designed to minimize the magnetic couplingbetween the magnetic bias field, such as from a permanent magnet, andthe pick-up coil. The position of the pick-up coil with respect to themagnetic bias field may be optimized for maximum signal from the filmand minimal signal due to the magnetic field from the bias field.

In another embodiment, the system comprises a remote receiver which is astationary unit located at suitable position with reference to both thewearer and nursing staff (for example, in the wearer's or patient'sbedroom) or only with reference to the nursing staff (for example, inthe office of the nursing staff).

In yet another embodiment, the one or more sensing device(s) comprises aresonant electric circuit instead of a magnetoelastic film. Saidembodiment comprises a first and a second electrode of a LC-circuit orLRC-circuit. Said first and second electrode is arranged as part of, orclose to the fastening device of said absorbent article. The fasteningdevice is further provided with a conductive area, e.g. a metal film,such that when the fastening device of the absorbent article iscorrectly closed, the conductive area makes contact to both the firstand the second electrode, thereby short-circuiting said LC-circuit. Whensaid LC-circuit is excited by an interrogation signal the responsesignal will be zero or close to zero, and a frequency of said signalwould be different from a frequency of a signal detectable when thefastening device of said absorbent article is open or incorrectlyclosed. Said interrogation signal is a signal for exciting theLC-circuit. The excited LC-circuit, subsequently to the excitation,emits a radio frequency response signal. This response signal is read bythe reading device, which can be part of a remote receiver.

In a further embodiment, said system comprises an absorbent articleprovided with a resonant electric circuit such as a LC or LRC-circuit.Said resonant electric circuit is of a sufficiently small size such thatit can be arranged as part of or close to the fastening device of saidabsorbent article. The fastening device is further provided with ashielding means, e.g. a metal foil or metal film, such that when thefastening device of the absorbent article is correctly closed, theshielding area comes in such a position that it covers completely orsuch a big part of the resonant electrical circuit that said shieldingmeans disperses an incoming radio-frequent signal, such that theunderlying resonant electrical circuit does not resonate, or resonatesvery little.

The resonant electrical circuit is preferably arranged in the so called“Tape Landing Zone”, i.e. the area of the fastening device of theabsorbent article where the adhesive fastening tab is fastened. In ahook-and-loop system the corresponding zone would be the “loop zone”.

According to another aspect, the disclosure relates to the use of saidsystem in the care of children and adults suffering from incontinenceand/or psychological illnesses, such as dementia.

EXAMPLES

Examples (and accompanying figures) 1-5 given below illustrateembodiments of the invention, and describe several possible embodimentsof said absorbent article which is comprised in the system. Theseexamples are present to exemplify the invention but not intended tolimit in any way the invention as described herein.

FIGS. 1 and 2 (taken together), and FIG. 3 shows two differentembodiments of the invention.

Example 1

In FIG. 1, the belt-diaper (1) has a general T-shaped configuration andcomprise an absorbent structure (2) placed in between a liquid permeabletopsheet (4) and a liquid impermeable backsheet (5). The belt-diaperfurther comprises a fastening device in the shape of a belt (3). Thebelt consists of a first and a second belt part (7, 8) in the shownembodiment.

The belt-diaper further comprises fastening system in the shape of abelt fastening hook (6) which attaches directly onto the second beltpart (8). The fastening system further includes diaper fastening hooks(12, 13). The belt comprises a nonwoven laminate with a layer ofspunbonded nonwoven placed in-between and thermally bonded to two layersof carded nonwoven. In this embodiment, the nonwoven layers consist ofpolypropylene fibers. Each layer has a surface weight of about 22 g/m².

The diaper fastening hooks (12, 13) are placed on the liquid permeabletopsheet (4) of the diaper (1) and attach directly onto the outwardfacing part of belt (3), as illustrated in FIG. 2. Each diaper fasteninghook comprises a permanent magnet (15, 16) placed between the liquidpermeable topsheet (4) and the outer surface of the diaper fasteninghook (15, 16). Further details of this arrangement are shown in FIGS.4-5. The permanent magnet may be in the form of small metallic pieces ofvarious shapes and sizes, powder, granules, film, magnetic ink, or otherforms.

A plurality of magneto-elastic films, for example, three films, arepositioned inside the first belt part (7) between the carded nonwovenlayer facing away from the user during use and the middle spunbondednonwoven layer in the belt laminate. This is illustrated by threerectangular magnetoelastic films (20) shown in FIGS. 1 and 2. In furtherembodiments said plurality of magneto-elastic films may be placed in alengthwise or crosswise direction of the fastening system. Placing themin a lengthwise direction allows users of different sizes to use theabsorbent article without severely affecting the functionality of theinvention.

In all embodiments, the films are preferably encapsulated in order toprotect them from mechanical pressure.

In a further embodiment, several more sensors (20), which may possessdifferent resonance frequencies, are placed in the absorbing article.The placement may be in the rear, in the front and on the sides of thediaper.

The placement of the sensors 20 in FIG. 1 are only to be considered asexamples.

The belt diaper further comprises a front part (19) intended to be wornagainst the wearer's abdomen during use. A rear part (17), intended tobe worn against the wearer's back during use and a crotch part (18),placed between the front part (19) and the rear part (17), intended tobe worn against the wearer's genitals during use. The belt (3) isattached to the rear part (17) of the diaper (1).

FIG. 2 shows the diaper (1) just before fastening of the front part (19)of the diaper (1) to the belt (3). FIG. 1 should also be referred to forreferences to other parts of the diaper. The first belt part (7) isattached to the second belt part (8) via belt fastening hook (6). Bydoing this, the plurality of magneto elastic films (20) are exposed andpositioned in close relationship to the diaper fastening hooks (12, 13)and the permanent magnets (15, 16). The absorbent core, liquidimpermeable backsheet and the liquid permeable topsheet shown in thebelt-diaper in FIG. 1 may have, where appropriate, the sameconfiguration as the open diaper described in FIG. 3.

A remote unit in the form of a hand held unit or in the form of astationary unit may then be used to establish a first frequency A whichcorresponds to a closed diaper. This frequency A can at any later stagebe used to correlate a new measurement of a second frequency B. If thefirst frequency A is lower than the second frequency B then thepermanent magnets (15, 16) are displaced in relationship to theplurality of magneto elastic films 20. This displacement can becorrelated to the event that the fastening system of the diaper isdisabled or that the function of the fastening system is reduced. Whenthe diaper fastening system is disabled, the diaper is not in conformitywith the wearer's body and the risk of leakage is thus much higher thanbefore. The alarm signal resulting would cause a nursing aid to lookinto the wearer's actual situation. In one embodiment, the frequency Ais stored in the hand held unit. In another embodiment, the frequency Ais sent directly or indirectly to a computer which compares thefrequency A with a later measured frequency B.

Both the frequencies A and B may also be compared to predeterminedvalues corresponding to open or closed/disabled diaper.

Example 2

FIG. 3 a and FIG. 3 b show a further embodiment of the invention. FIG. 3a displays a diaper with tape tabs (307, 308) and two loop fasteningzones (320, 321) placed on the liquid impermeable backsheet (302). Thetape tabs 307, 308 are further provided with hook areas 307 a, 307 b.The hook areas are further each provided with a permanent magnet 340,341. This arrangement is futher described in connection with FIG. 4.

The loop fastening zones (320, 321) comprises a conventional loopmaterial and will therefore not be described further. Two magnetoelasticfilms 331, 332 are positioned between the loop fastening zones 320, 321and the liquid impermeable backsheet. When the diaper is worn, thefastening system in the shape of the tape tabs (307, 308) with hookareas 307 a, 308 a and permanent magnet areas 340, 341 and the loopfastening zone (320, 321) will be close in relation to themagnetoelastic films. The frequency can then be established as describedin Example 1. When the diaper is unfastened, the displacement results inan alarm signal to the wearer or nursing aid as before.

The wetting point is an area of the diaper surface onto where the bodyliquid or body waste first comes into contact. Obviously, it is notpossible in practice to establish any specific point or area in thisregard, although it can be generally accepted that the body liquid orwaste will be delivered to the diaper within a given, limited areathereof. In general, this area is displaced slightly towards the frontof the diaper part, in the case of both male and female wearers. Sincethe dispersion of the liquid in the first absorbent layer, i.e. theacquisition layer, is only slight, it is sufficient for this layer tocover solely the area of the diaper where wetting is most likely tooccur. Accordingly, such aspects may be analyzed and considered whenplacing sensoring devices in an absorbent article, such as the diapercomprising the system.

The diaper illustrated in FIG. 3 is comprised of a liquid-permeable topsheet 301, for instance, a non-woven or perforated plastic film, aliquid impermeable back sheet 302, for instance, a plastic film or ahydrophobic non-woven material, and an absorbent structure 303 enclosedbetween the two layers 301, 302.

The diaper is intended to embrace the lower part of the wearer's trunk,in the manner of a pair of absorbent underpants. The diaper is providedwith a back part 304 which, when the diaper is worn, will be locatedrearwardly on the wearer, a front part 305, which when the diaper isworn will be located forwardly on the wearer, and a narrower crotch part306 which extends between the back part 304 and the front part 305 ofthe diaper and which, when the diaper is worn, is located in the crotchregion of the wearer, between the thighs thereof. Fastener tabs 307,308, with hook material, 307 a, 308 a, are provided on the side edges309, 310 of the back part 304 extending in the longitudinal direction ofthe diaper, close to the rear waist edge 311 of said diaper, so as toenable the diaper to be secured in the desired pants-like form. When thediaper is to be used, the fastened tabs 307, 308 are fastened to theouter surface of the front diaper part 305, close to the forward waistedge 312, thereby holding the diaper together around the wearer's waist.

The diaper illustrated in FIG. 3 also includes prestretched elasticdevices 313, 314 which extend along the longitudinal side edges of thediaper in the crotch part 306. The elastic devices 313, 314 may consistof any suitable material, such as elastic foam, elastic bands or coveredelastic threads. For the sake of convenience, the elastic devices 313,314 have been shown in a stretched state.

The absorbent structure 303 is comprised of mutually different layers.Nearest to the liquid permeable top sheet 301 is a thin cellulosefluff-pulp layer 315 of high critical bulk, large pore volume and lowliquid-dispersion ability. By critical bulk is meant the bulk at which acellulose body will neither collapse nor expand when becoming wet. Acellulose fluff-pulp of high critical bulk will retain an open structureof large pore volume even when wet.

Seen in a direction towards the liquid-impermeable back sheet 302, therethen follows a first absorbent layer 316, which is comprised ofcellulose fluff-pulp of large pore volume, high wet resilience and lowliquid-dispersion ability, and a second absorbent layer 317 comprised ofcellulose fluff-pulp of low pore volume, low wet resiliency and highliquid-dispersion ability. Both absorbent layers also includesuperabsorbent material.

The first absorbent layer 316, has an oval shape and is locatedgenerally in the crotch part 306 of the diaper, around the so-calledwetting point. In other embodiments said layer 316 has a rectangularshape or other suitable shape.

The first receiving layer, i.e. the acquisition layer, in the diaperthus functions as a receiving area for discharged body liquid or waste.

CTMP fluff, CF fluff, wadding or foam is suitable for use in the firstabsorbent layer. SAP may be added in different proportions to this layeras well. The first absorbent layer 316 may also contain between 2-30%,such as 2-15% superabsorbent material calculated on the total dry weightof the layer in that area in which the superabsorbent material is mixed.The superabsorbent may be distributed generally uniformly in the layer,within at least one area or region thereof, and is intended to bind anyliquid that remains in the layer, even when the layer has been drainedby the second absorbent layer 317, which may be a wicking layer.

As mentioned previously, the superabsorbent material in the firstabsorbent layer should preferably have a high gel-strength, to retain anopen fibre structure even when becoming wet.

The second absorbent layer 317 also contains superabsorbent material,which may be in the form of one or more layers of flakes, fibres,granules, powder or the like. The layer extends either over the whole ofthe absorbent layer 317 or is restricted to at least one area thereof.This area may, for instance, be slightly larger than the absorbent layer316 and, similar to said layer, may be limited essentially to the crotchpart of the diaper.

The proportion of superabsorbent included in the second absorbent layer317 will preferably be between 2 and 60%, preferably between 19 and 50%,calculated as a fraction of the total dry weight of the layer. The superabsorbent in the second absorbent layer 317 will preferably have a highgel-strength, i.e., has the ability to swell substantially unaffected bynormally occurring pressure forces, so as not to block or impededispersion of the liquid. Characteristic of these super absorbents isthat they have a high degree of cross-linking which renders them moredifficult to compress in comparison with a gel that has a lower degreeof cross linking.

The fluff pulp in layer 317 of the second absorbent layer may comprisesubstantially fluff-pulp or some other absorbent material having a highliquid-dispersion capability. Chemically produced fluff-pulps, ofcellulose material, generally fulfill this. The final fibres may have aweight of 140-190 μg/m, a low degree of stiffness and low wet-stability,and a critical bulk beneath 8 cm³/g at 2.5 kPa.

The second layer 317 may also comprise a chosen fluff pulp, such asCTMP-pulp or chemical pulp.

Thus, discharged body fluid or waste is first collected in the firstabsorbent layer 316, which function as a buffer, or reservoir, thislayer being successively drained as the second absorbent layer 317,absorbs and disperses the liquid waste.

It will be understood that the illustrated and described diaper ismerely intended to exemplify the invention and shall not be consideredto limit the scope of the invention. For instance, the shape of thediaper and its construction in other respects may be varied. Similarly,the first absorbent layer 316 may fully cover the second absorbentlayer. Furthermore, the thin cellulose fluff-pulp layer 315 locatednearest to the liquid-permeable top sheet layer 301, may be omitted.

It should also be noted that a diaper, as used herein, is particularlyused in conjunction with incontinence, but that the invention is notlimited to this particular use or any particular size or type of diaperimplied thereby, but may be any diaper obvious to the person skilled inthe art.

Example 3

FIG. 4 a displays a hook fastening device (401) comprising a carriermaterial, for example, a spunbonded nonwoven with a basis weight ofabout 25-60 g/m². The carrier material is preferably made ofpolyproplyene fibers but any conventional material can be used. Thecarrier material further comprises a permanent magnet (402). Thepermanent magnet (402) is held in place by the hook material (403) whichis adhered onto the carrier material with conventional hot-meltadhesive. Optionally the magnet may be adhered to the carrier materialdirectly. The hook material (403) holds the magnet in place so that theposition of the magnet is always correlated with the position of thehook material.

FIG. 4 b shows a cross-sectional view along the line I-I for oneembodiment of the hook fastening device.

FIG. 5 a discloses another embodiment of a fastening device. In thisembodiment the permanent magnet is free from said hook material. Thisexposes the magnetoelastic film to a stronger bias-field, which might befavorable, when the article is worn.

It should be noted that the hook material may be replaced by an adhesivefilm or any other known fastening material known in the art. If thefastening system consists of a magnetic fastening device, such as usedon purses or similar, there is no need for an additional permanentmagnet. Instead the bias-field from the magnetic fastening system may beused in the system according to the invention. The permanent magnet asshown is rectangular in shape but may in other embodiments be in theform of small metallic pieces of various shapes and sizes (such as thoseused domestically as kitchen pin-up devices on the refrigerator),powder, granules, film, magnetic ink, and other existing forms.

The thickness of the magnet may also range between about 30 μm-5 mm,such as about 40 μm-3 mm. 70 μm-2 mm, 100 μm-2 mm, 500 μm-2 mm. 1 mm-2mm. 30 μm-1 mm. 30 μm-500 μm, or 30 μm-200 μm.

A “thin” magnet may have a thickness of about 40 μm, while a typical“thick” magnet may have a thickness of about 1 mm. The length and widthof the magnet is preferably adapted for each use. Typically the magnethas at least one dimension, such as a length, width, diameter orsimilar, of at least 5 mm, 10 mm, 2-10 mm, 20 mm, 30 mm, 40 mm, 50 mm orabout 10-20 mm, such as 10-30 mm, 10-40 mm, 10-50 mm, 10-100 mm.Different magnets gives different bias-fields which affect the resonanceof the magnetoelastic film. A plurality of permanent magnets may be usedin one embodiment.

Example 4

An excitation device is used to excite the resonant entity of theembodiments of the present invention. Said excitation device comprisesin one embodiment an excitation coil, and suitable circuitry and powersupply to provide said coil with a signal suitable for generating aradio frequency excitation field.

A reading device is used to pick up the response signal emitted from theresonant entity. Said reading device comprises in one embodiment apickup coil, and suitable circuitry and power supply to receive andextract frequency data from said response signal. Said reading devicefurther comprises a display for displaying said frequency. In a furtherembodiment said reading device further comprises circuitry or softwareto determine whether a frequency refers to a correctly fastenedabsorbent article or to a an unfastened/removed absorbent article.

Example 5

In a further embodiment of the present invention said absorbent articleis provided with a seal means. Said seal means comprises a first partand a second part.

Said first part is provided with an influencing means. Said second partis provided with a resonant entity, capable of being influenced by saidinfluencing means.

Said first part and said second part are devised to be able to attach toeach other, i.e. the seal is closed, such that when they are attachedthe influencing means is influencing the resonant entity. When takenapart from each other, i.e. the seal is broken, the influencing means donot influence said resonant entity to any significant degree.

The seal means is arranged at the absorbent article in such a way that,when the absorbent article is properly attached to the user, and theseal means is closed, it is not possible to remove or displace theabsorbent article without breaking the seal.

When the seal is broken the response from the resonant entity is alteredand the event can be detected.

Preferably, the influencing means is provided within or upon an adhesivetape, and when the absorbent article, e.g. a trouser type diaper, isproperly put into place, the adhesive tape is attached to the partcomprising the resonant entity, thereby influencing the resonant entity.

When the trouser type diaper is removed or displaced, intentionally orunintentionally, the tape will be displaced from its position, and theinfluence on the resonant entity is altered. The response from saidentity is thus altered and the event can be detected.

The invention should not be considered as limited by the abovedescription; rather the scope and limitations of the invention aredefined by the enclosed claims, and equivalents thereof.

What is claims is:
 1. A system comprising means for detecting when anabsorbent article is unfastened or removed from a body of a wearer, bydetecting displacement of one part of the absorbent article from aposition in contact with another part of the absorbent article to aposition not in contact with the another part of the absorbent article,and means for conveying an alarm signal if the absorbent article isunfastened or removed from the body of the wearer, wherein the absorbentarticle comprises at least one absorbent layer and an object to bedisplaced, and the means for detecting includes a remote receiver thatis remote from the absorbent article.
 2. The system according to claim1, wherein said means for detecting detects oscillational differencesarising due to an increase or a decrease in a magnetic bias-fieldcorresponding to a displacement of said object.
 3. The system accordingto claim 2, wherein said means for detecting is a magnetoelastic film.4. The system according to claim 1, wherein said means for detectingcomprises a radiofrequency electrical circuit.
 5. The system accordingto claim 4, wherein said radiofrequency electrical circuit is arrangedsuch that it becomes short-circuited when said absorbent article isfastened correctly to the body of the wearer.
 6. The system according toclaim 5, wherein said radiofrequency electrical circuit is arranged suchthat it is not short-circuited when said absorbent article is unfastenedor removed from the body of the wearer.
 7. The system according to claim6, further comprising an excitation device capable of emitting a radiofrequency excitation signal.
 8. The system according to claim 7, whereinsaid remote receiver is capable of reading a radio frequency signalemitted from the radiofrequency electrical circuit.
 9. The systemaccording to claim 1, wherein said remote receiver is a handheld unit.10. The system according to claim 1, wherein said remote receiver is astationary unit.
 11. The system according to claim 1, further comprisingmeans for detecting when said article is wet, and also comprising means,connected to said means for detecting when said article is wet, forconveying an alarm signal, signalling that said article is wet.
 12. Asystem comprising a sensor for detecting when an absorbent article isunfastened or removed from a body of a wearer, by detecting displacementof one part of the absorbent article from a position in contact withanother part of the absorbent article to a position not in contact withthe another part of the absorbent article, and an alarm for conveying analarm signal if the absorbent article is unfastened or removed from thebody of the wearer, wherein the absorbent article comprises at least oneabsorbent layer and an object to be displaced, and the sensor includes aremote receiver that is remote from the absorbent article.
 13. Thesystem according to claim 12, wherein said sensor detects oscillationaldifferences arising due to an increase or a decrease in a magneticbias-field corresponding to a displacement of said object.
 14. Thesystem according to claim 13, wherein said sensor includes amagnetoelastic film.
 15. The system according to claim 12, wherein saidsensor includes a radiofrequency electrical circuit.
 16. The systemaccording to claim 15, wherein said radiofrequency electrical circuit isarranged such that it becomes short-circuited when said absorbentarticle is fastened correctly to the body of the wearer.
 17. The systemaccording to claim 16, wherein said radiofrequency electrical circuit isarranged such that it is not short-circuited when said absorbent articleis unfastened or removed from the body of the wearer.
 18. The systemaccording to claim 17, further comprising an excitation device capableof emitting a radio frequency excitation signal.
 19. The systemaccording to claim 18, wherein said remote receiver is capable ofreading a radio frequency signal emitted from the radiofrequencyelectrical circuit.
 20. The system according to claim 12, wherein saidremote receiver is a handheld unit.
 21. The system according to claim12, wherein said remote receiver is a stationary unit.
 22. The systemaccording to claim 12, further comprising means for detecting when saidarticle is wet, and also comprising means, connected to said means fordetecting when said article is wet, for conveying an alarm signal,signalling that said article is wet.
 23. A system comprising: anabsorbent article including a liquid permeable topsheet, a liquidimpermeable bottom sheet, and an absorbent core between the liquidpermeable topsheet and the liquid impermeable bottom sheet, means fordetecting when the absorbent article is unfastened, and means forconveying an alarm signal if the absorbent article is unfastened. 24.The system according to claim 1, wherein the means for detectingincludes a resonant entity.
 25. The system according to claim 12,wherein the sensor includes a resonant entity.